A system of carrying out recording and reproduction by using a signal used for ordinary television broadcasting and the like (hereafter referred to as a video signal) is shown in FIG. 11. In FIG. 11, numeral 101 designates an image pickup apparatus, numeral 102 designates a recording apparatus, numeral 103 designates a reproduction apparatus, and numeral 105 designates a display apparatus. The image pickup apparatus 101 is generally referred to as a television camera or a video camera and outputs a video signal. The recording apparatus 102 is a VTR (Video Tape Recorder) or a disc recorder of recording the output signal of the image pickup apparatus 101, and the reproduction apparatus 103 reproduces a signal depending on information recorded on a recording medium by the recording apparatus 102. The display apparatus 105 displays the output signal from the reproduction apparatus 103. In addition, the display apparatus 105 may directly display the signal from the image pickup apparatus 101.
On the other hand, needs for making movies electronic are increasing owing to the progress of HD (High Definition) broadcasting equipment in recent years. In other words, demand for electronic cinema systems and the like wherein a video signal to be recorded on a film (hereafter referred to as a film signal) is recorded on a video tape or the like is increasing. Hence, the image pickup apparatus 101 shown in FIG. 11 is required to have a function capable of handling both the film signal and the video signal. To meet these needs, in the image pickup apparatus 101, conversion is carried out so that an image picked up is output as a film signal.
The operation of a conventional film or video image pickup signal recording/reproduction system will be described below by using FIGS. 11 and 12.
When a video signal used for ordinary television broadcasting and the like is processed in the configuration of the system shown in FIG. 11, the image pickup apparatus 101 outputs an image pickup signal having a format of 1080/60i (i: interlace, hereafter represented by i) or 720/60p (p: progressive, hereafter represented by p) in the case of the HD system. The recording apparatus102, the reproduction apparatus 103 and the display apparatus 105, connected on the output side of the image pickup apparatus 101, also conform to the system matching the format of the image pickup signal of the image pickup apparatus 101. The field frequency is basically fixed at 60 Hz, although it differs depending on the scanning system (i or p).
In addition, with respect to a gamma characteristic, a video signal gamma curve (a gamma curve for a broadcasting camera) shown in FIG. 12 is used. In FIG. 12, an input light amount of 100% is an input light amount having a value of 100 IRE (0.7 VPP) (regarding the level of the output signal, 0.7 VPP is taken as 100% and represented by 100 IRE) as the level of the output signal of the image pickup apparatus 101. The specifications of the video signal gamma curve are determined as described above (the broadcasting camera standard: ITU-R BT709). Furthermore, the aperture adjustment of the image pickup apparatus 101 is carried out so that the level of flesh color becomes 60 to 70 IRE. FIG. 13(a) shows a state obtained when the output of the image pickup apparatus 101 using this kind of video signal gamma curve is viewed by the display apparatus 105, such as a CRT monitor, based on the specifications of the gamma curve for a broadcasting camera.
On the other hand, when a film signal is processed in the system shown in FIG. 11, the frame frequency is basically 24Hz (the frame frequency of a movie) and the scanning system is 24p (24progressively-scanned signal) in the image pickup apparatus 101. In addition, in order that variable-speed image pickup is attained just as in the case of a film camera, it is required to obtain image pickup signals having various frame rates. Furthermore, in that case, the recording apparatus 102, the reproduction apparatus 103 and the display apparatus 105, provided on the output side of the image pickup apparatus 101, are also required to conform to the various frame rates. With respect to this, in Japanese Laid-open Patent Application No. 2002-152569 applied by the applicant of the present invention, processing conforming to the above-mentioned various frame rates by using a conventional video image pickup apparatus has been proposed. By this proposal, processing for a variable frame frequency is made easy.
In addition, when a film signal is generated by using the image pickup apparatus 101, the image pickup apparatus 101 is required to have gradation in a wide dynamic range. For this purpose, as shown in FIG. 12, the operation of almost linearly converting the gradations of all the signals in the dynamic range by using the film signal gamma curve characteristic, instead of making correction by using the conventional video signal gamma curve characteristic, has been introduced to video camera recorders in recent years. When the signal obtained in this way is recorded finally on a film, it is recorded on the film via a conversion table matching the characteristic of the film.
As described above, even if an image pickup signal recording/reproduction system of processing a video signal is used, by modifying part thereof, it has become possible to configure an image pickup signal recording/reproduction system for a film signal.
However, in the above-mentioned conventional image pickup signal recording/reproduction system, when the image pickup apparatus 101 outputs a film signal, the image pickup apparatus 101 uses a gamma curve characteristic (see the film signal gamma curve shown in FIG. 12) wherein the gradations of all the signals in the dynamic range are made almost uniform, whereby the image pickup signal reproduced by the display apparatus 105 is wholly dark as shown in FIG. 13(b) in comparison with the case when a video signal is output, and an image with low contrast is obtained. For example, the level of the output signal is 50 to 60 IRE and the level of the flesh color of a human face becomes 30 to 40 IRE when the input light amount is 100%. This causes a problem of making the confirmation of the image pickup signal difficult.